Generally, such a mixing valve apparatus includes a casing formed with a first inlet for the high temperature fluid, a second inlet for the low temperature fluid, a mixing chamber which is in communication with the first and second inlets, and in which the high temperature fluid and the low temperature fluid are mixed with each other, and an outlet which is in communication with the mixing chamber, with inlet valves for the high temperature fluid and the low temperature fluid arranged in association with the first and second inlets, respectively.
It is widely known that the mixing valve apparatus should have an automatic regulating function whereby the desired temperature of the mixed fluid is kept constant even upon the variation in the fluid supply pressure or in the consumption demand of the mixed fluid, and should moreover be safe in use. However, in known apparatuses, the regulating device for regulating the temperature of the mixed fluid is usually composed of deformable, temperature-sensitive elements such as bimetal elements arranged in association with the inlet valves for the high temperature fluid and low temperature fluid, respectively, and has a relatively simple characteristic whereby the temperature-sensitive elements control the opening degree of relevant inlet solely in response to the temperature of the mixed fluid, so that the device is not capable of performing the above mentioned desirable functions. Moreover, in particular situations where the supply of the low temperature fluid is interrupted by some reason, when the faucets at the mixed fluid discharge terminal are opened, in case of known mixing valve apparatus with the above-mentioned simple temperature regulating device, steam or the like high temperature fluid alone may be discharged from the faucets whereby it is difficult to sufficiently preserve the safety for users.